If not otherwise specified: all dimensions are in mm, all weights and loads are in kg.

1.0 General principles

Power take-offs connect the vehicle‘s engine with the units to be driven, for example compressors or hydraulic pumps.

Careful selection of the power take-off and a study of the installation situation are essential for subsequent trouble-free operation of the vehicle.

MAN (for address see “Publisher“ above) will be happy to provide advice in this regard.

The guidelines for power take-offs are not designed to replace the vehicles‘ operating instructions.

Power take-offs not offered ex works for the respective vehicle are installed at the installer‘s risk.

Power take-offs can be installed at the following locations, in some cases at several of them at once:

• On the engine

- On the front end of the engine (e.g. on the front end of the crankshaft, using a twin-groove V-belt pulley, as a pump directly connected to the air compressor)

- On the engine rear (e.g. camshaft power take-off, flywheel-side power take-off)

• On the gearbox

• On the transfer case.

When selecting a power take-off, the following factors must be taken into consideration:

• Permissible torques

• Direction of rotation

• Impact factors

• Service life

• Critical engine speed

• Maximum length of the propshaft

• The maximum deflection angle and installation space for the propshaft

• Transmission ratio

• Gearbox technology (OD/DD)

• Cooling (no trapped heat at power take-off)

• Assembly and access

• Pump attachment

• The instructions of the power take-off manufacturer

• The instructions of the pump manufacturer

• The instructions of the propshaft manufacturer

The manufacturers of power take-offs have issued their own publications, which provide detailed information on:

• Correct choice of power take-off

• Correct utilisation

• Avoidance and elimination of vibration.

The maximum torque allowed for the power take-off can only be utilised if it is operated without any impacts and vibrations. This is rarely possible, which is why in practice impact factors must be taken into consideration when selecting the power take-off. A jolt or impact is understood to be a rapid increase in torque that decreases again rapidly after a very short period of time. The quotient of maximum and minimum torque is known as the impact factor.

The dimensioning must be based on the maximum occurring torque including the impact factor.

Power take-offs must be protected against overheating; if necessary, the fan wheel offered by MAN must be

installed. Besides the fan wheel, various other heat-exchanger solutions for cooling gearboxes and power take-offs are available. These make it possible to achieve fatigue strength for certain types of power take-off. More detailed information can be obtained from MAN (for address see “Publisher“ above).

Heat must not be trapped; inadequate heat dissipation will cause damage.

Note on gearbox-oil temperature:

The gearbox and the power take-off‘s nominal oil temperature may not exceed 110°C during operation.

Peak temperatures of max. 130°C are still permissible for brief periods (a maximum of 30 minutes).

If a check reveals that the oil temperature reaches higher values, then some form of external cooling (e.g. a fan wheel) must be provided.

If parts of the engine enclosure have to be removed in order to install power take-offs, they must be replaced by suitable items provided by the installing company. It must be ensured that excessive noise is not emitted.

The instructions in the section of the series-editions, chapter III Chassis, 6.3 “Engine environment“ must be observed.

Power take-offs are not designed to accept radial bearing loads imposed by chains or V-belt drives.

For this reason, chain sprockets or V-belt pulleys may not to be connected directly to the power take-off.

If the equipment to be driven could overload the power take-off, some form of overload protection must be installed. This also applies if only occasional peak torques beyond the permitted limit occur. MAN workshops can use the standard interface to configure and provide wiring for speed and torque limiters for TG vehicles

More detailed descriptions of the ZDR-Interfaces, pin assignments and information on parameterisation can be found in the series-editions, chapter III-Chassis, 8.3 “ZDR-Interfaces on the vehicle, preparations for the body“.

As is customary in mechanical engineering, all directions of rotation are quoted “looking at the shaft journal“, that is to say at the output point.

The rotational speed at the power take-off‘s output is calculated by multiplying the engine speed by the respective PTO‘s speed factor.

The following are not permitted:

• Engine speeds < 800/minute with the power take-off engaged and under load

• Even-numbered transmission ratios such as 1:1, 1:2 etc., since vibration could occur as a result of resonance

At engine speeds of < 800/minute, unfavourable relations in conjunction with drive shafts may lead to the development of excessive noise and vibrations on the power take-offs.

1.1 Calculating power and torque

Before the correct power take-off can be selected, the following details of the equipment it is to drive must be available:

The output torque stated for clutch- and engine-dependent power take-offs connected to the gearbox is based on a PTO output with a nominal speed of 1500 rpm. Output torque decreases at higher speeds.

As a constant, output power at 1500 rpm is used here. Using this constant it is then possible to calculate the available output torque at higher speeds.

Power and torque can be calculated using the formulae cited in the “Calculations” chapter (in the booklet applicable to the respective model range). The corresponding formulae are explained using examples.

1.2 Propshaft connection to power take-off

With regard to the propshaft connection, the fundamentals laid down in the “Propshaft” section of the chapter 6.5 “Gearbox and propshafts” (n the booklet applicable to the respective model range) apply.

The following conditions apply to the deflection angle of both single-plane and three-dimensional shaft systems:

• Deflection angle ≤ 7°, a tolerance of +1° is permissible

• Absolute difference in angle of ≤ 1° between the two deflection angles of a shaft; 0° is to be aimed for.

Fig. 01: Geometry of a propshaft train for power take-offs

1) Gearbox

2) Unit

3+4) Flanges must be aligned parallel

5) Deflection angles of the propshaft

When specifying the length of the propshaft, the length of any flexible coupling that may have to be installed must be taken into consideration.

The stated values apply to both single-plane and three-dimensional propshaft systems.

In the case of three-dimensional propshaft systems, the resultant three-dimensional deflection angle must be taken into account. Exceptions to the stated values must be expressly approved by MAN (for address see “Publisher” above).

Propshafts close to where persons move or work must be encased or covered.

In certain cases it may be necessary to modify individual cross members in order to ensure a permissible angle for the propshaft. MAN offers its own solutions for this.

On the TGL/TGM model range, for example, a height-adjustable portal cross member can be installed. If one or more power take-offs is/are fitted to the gearbox ex-works, then the first frame cross member (portal cross member) behind the gearbox is adjustable in height. This allows the installation of the propshafts on the power take-off to take the maximum permissible deflection angle of 7° (+1° tolerance) into account. In its installed position on series-production vehicles the cross member, including bolt head, protrudes above the frame top edge by 70 mm.

This height-adjustable cross member can be retrofitted at a later date (e.g. when retrofitting a power take-off).

If these solutions are inadequate, the planned measures must be approved by MAN beforehand (for address see „Publisher“ above).

Fig. 02: Height-adjustable portal cross member for power take-off on gearbox

1) Driving direction

2.0 Regulating engine speed

Whether the vehicle is being driven or used to operate power take-offs, the power required from the engine is not normally constant. The fluctuation in power requirement at a constant speed of rotation has to be equalised by varying the amount of injected fuel.

At a constant speed of rotation, the following therefore applies:

• Less power required - less fuel injected

• More power required - more fuel injected.

Depending on the vehicle’s body and its intended purpose, the power take-off and therefore the engine are required to run either at a minimum, a constant or a maximum speed. In most cases more than one of these requirements has to be fulfilled simultaneously. All MAN diesel engines regulate speed and load by means of EDC (EDC= Electronic Diesel Control). Interventions by the bodybuilder are made via the ISC (Intermediate Speed Control) interface.

The ISC can also be actuated via the CSM (customer-specific control module).

The set speeds are maintained at a constant level even when the load varies; the accuracy of this system is always greater than that of a mechanical system.

Lower speeds when operating the power take-off do not necessarily result in lower consumption or less noise.

The engines are optimised for certain operating situations that ensure economical and quiet operation.

2.1 Regulating the engine speed using cruise-control controls

MAN trucks and tractor units are fitted with a cruise control lever to regulate the vehicle’s speed. Alternatively, the cruise-control function can also be controlled by means of the function keys on the multifunction steering wheel.

At road speeds ≤ 20 km/h this allows the engine speed to be regulated even without intervention in the ZDR interface.

The memory button (Fig. 03 Pos. 1 / Fig. 04 Pos. 1) allows a constant speed to be set, with the + and - buttons setting a working speed between an upper and lower limit. This then remains constant until the off button (Fig. 03 Pos. 2 / Fig. 04 Pos. 2) is pressed or another switch-off condition (e.g. operating the brakes) occurs.

The speed value can be permanently saved by pressing the memory button 1 (Fig. 03 Pos. 1) for 2 seconds so that, even after the engine has been turned off and/or the vehicle has been driven a short distance, it can be called-up again by briefly pressing the memory button (Fig. 03 Pos. 1).

Fig. 03: Layout and function of cruise control lever

1) Memory button

2) Off button

Fig. 04: Layout and function of the multifunction steering wheel

1) Memory button

2) Off button

2.2 Engine speed regulation via the ISC interface

The EDC control unit can be programmed to obtain suitable engine speed settings when power take-offs are to be used.

The following can be set:

• Speeds (i.e. reduced top speed when power take-off is in use)

• Intermediate speeds

• Speed limits if intermediate speed control is required (e.g. for protection of the unit)

• Regulating behaviour and characteristic

• Switching preconditions.

The body-mounted equipment control system intervenes (e.g. by a switching signal to run up to a predetermined intermediate speed) and registers the operating status (e.g. parking brake, gearbox in neutral, power take-off switch setting) via the ISC interface. In order for these programmable options to be used, the following information is required:

• ISC interface (for the 2000 model ranges L2000, M2000 and F2000)

• Interface for intermediate speed control at the vehicle management computer ISC at VMC (standard equipment on all vehicles in the TG ranges).

• Customer-specific control module (optional, standard equipment on all vehicles in the TG ranges).

A detailed description of the VMC and CSM ZDR-Interfaces with examples of use and current documentation on the hard and software can be found in the series-editions, chapter III-chassis, 8.3 “ZDR-Interfaces on the vehicle, preparations for the body“ booklet. Please note that only the interface is offered ex works but none of the wiring.

Industry-specific parameters can already be programmed at the factory if the desired values are provided in good time to the MAN salesperson by the bodybuilder. Changes can be made at a later date using the MAN-cats® diagnostic system.

2.3 Starting and stopping the engine from outside the cab

Certain body-side equipment requires that the vehicle’s engine can be started or stopped from outside the cab.

• Gearbox neutral selection switch; the engine can be started only if neutral has been selected, i.e. if no gear is engaged.

• Parking brake signal recognition; the engine can be started only if the parking brake has been applied.

• Start inhibit relay; the engine cannot be started again if it is already running.

Retrofitting the interface is possible but requires detailed knowledge of electrical/electronic systems and the MAN on-board network. We therefore advise ordering it from the factory.

The connecting cable is rolled up at the frame end. If the vehicle must not be moved during power take-off operation, we advise the additional fitting of a gear-shift inhibitor (see next section 2.4, „Gear-shift inhibitor and neutral selection switch“).

In the currently available TGL/TGM and TGS/TGX model ranges, in addition to the preparation at the frame end an engine start/stop facility beneath the front flap is also offered. The scope of functions is identical with that of the preparation at the frame end. However, no wiring harness is routed to the frame end.

Start/stop facilities developed by bodybuilders themselves must comply with the instructions as set down in the separate interface booklets.

2.4 Gear-shift inhibitor and neutral selection switch

On certain vehicles/types of body it is necessary to ensure that the power take-off can be engaged only if the vehicle is not in gear. This function is enabled by a neutral selection switch. A gear-shift inhibitor also covers the reverse situation, in that it prevents a gear being selected if the power take-off is already operating.

The MAN gear-shift inhibitor has the effect of an „exclusive OR“ switch, i.e. either a gear or the power take-off can be selected but not both at the same time.

In the case of vehicles with manual gearboxes, gear shift is mechanically inhibited, while in the case of vehicles with automatic gearboxes (TipMatic), gear shift is inhibited by means of software parameters.

We advise fitting a gear-shift inhibitor if engine speed is to be regulated and/or the engine is to be started from outside the cab and the vehicle cannot or must not be moved.

Fig. 05: Gear-shift inhibitor on manual gearbox

1) Gear-shift inhibitor

2.5 Stationary and non-stationary operation

As standard, power take-offs at the ends of gearboxes are designed for non-stationary operation, i.e. the power take-off can also be used while the vehicle is in motion in a moving-off gear. If gear-shift inhibition has been selected, the power take-off is switched to stationary operation. It can then only be operated when the vehicle is not moving. If more than one power take-off is installed, each one can be configured as either a stationary or a non-stationary power take-off.

If a power take-off configured as stationary is in operation, it is then not possible to engage gear, irrespective of whether a power take-off configured as non-stationary is present or in operation.

If only power take-offs configured as non-stationary are in operation, a moving-off gear can be engaged and the vehicle can be set in motion. Engaging gear and changing gear are possible only while the vehicle is not in motion.

In the case of the TipMatic automatic gearbox, stationary operation of a power take-off on the transfer case is not possible.

We advise fitting a gear-shift inhibitor if engine speed is to be regulated and/or the engine is to be started from outside the cab and the vehicle cannot or must not be moved.

3.0 Technical description of power take-offs

General note:

We wish to point out that the power take-off variants described in the guidelines to fitting bodies are possibly not available ex works. The power take-offs available as standard can be found in our currently applicable sales documents.

With regard to a change in the intended purpose of a vehicle and/or increasing its resale value, it is recommended that the vehicle be equipped with the necessary electrical preparation for retrofitting a power take-off.

3.1 MAN power take-offs

MAN manufactures the following power take-offs itself:

• V-belt pulley, engine-dependent; for description see Section 3.1.1

• Power take-off at the air compressor, engine-dependent; see Section 3.1.2

• Camshaft or flywheel-side power take-off, engine-dependent; for description see Section 3.1.3

• Power take-off on transfer case; depending on switch position, engine-, gearbox- or distance-dependent; for description see Section 3.1.4.

3.1.1 V-belt pulley

It is possible to fit a V-belt pulley with an effective diameter dw = Ø 242 mm with two grooves at the front end of the crankshaft on the D08 engine.

This V-belt pulley is installed at the factory in conjunction with a hydraulic pump, on the right-hand side in the direction of travel. In addition, a poly-V belt pulley with a diameter dw = Ø 224.8 mm is fitted to the crankshaft on vehicles fitted with air conditioning in order to drive the air-conditioning compressor.

L2000 / M2000: If air conditioning is fitted, this output point is occupied by the air-conditioning compressor.

TGL/TGM: Air conditioning and power take-off can be combined.

Narrow V-belts as per DIN 7753 (air-conditioning compressor) or internationally ISO 2790 are to be used as the transmission element. When calculating the power rating, proceed in accordance with DIN 7753 Part 2 or in accordance with the information provided by the belt manufacturer.

MAN can supply ex works various units driven by V-belts or poly V-belts, in particular hydraulic pumps.

The current range of products available for delivery can be found in the sales systems.

Hydraulic pumps fitted at the factory are fastened to the crankcase yoke.

Other units may also be mounted here if they do not weigh more than 11 kg.

3.1.2 Power take-off on air compressor

It is possible to flange hydraulic pumps directly onto the front ends of the two-cylinder air compressors on six-cylinder D28 engines (vehicles in the model ranges F2000, E2000 and TGA built up to 2003).

Fig. 07: Illustration on left: Output point on front end of two-cylinder air compressor on D28 Euro 3 engine

Illustration on right: Examples of hydraulic pumps on front end of two-cylinder air compressor on D28 Euro 3 engine

1) Alternator

2) Refrigerant compressor for cab air conditioning

3) Output at the two-cylinder air compressor

4) Single pump

5) Pump for hydraulic power steering

6) Tandem pump

7) Pump for hydraulic power steering

MAN can fit different hydraulic pumps ex works to the front end of the air compressor. Information on the sales program of the respective country can be obtained from the MAN salesperson or branch responsible. Drawings are available from MAN (for address see “Publisher” above).

Table 02: Technical specifications of hydraulic pumps for assembly on the air compressors of D28 engines

Engine

model

Speed factor

Hydraulic pump

Volume per revolution

in cm³

Pressure during constant operation in bar

D28

1,15

Hydraulic pump

32

210

Dual hydraulic pump

25 + 11

210

It is possible to flange hydraulic pumps directly onto the front ends of the single-cylinder air compressors on six-cylinder D20/26 engines (vehicles in the model ranges TGA, TGS and TGX).

An air compressor with a second output shaft is required for this purpose. The air compressor cannot subsequently be equipped with a second output shaft. Retrofitting requires replacement of the air compressor. Preparation for retrofitting pumps on air compressors is possible.

MAN can fit different hydraulic pumps ex works to the front end of the air compressor. Information on the sales program of the respective country can be obtained from the MAN salesperson or branch responsible. Drawings are available from MAN (for address see “Publisher” above).

Table 03: Technical specifications of hydraulic pumps for assembly on the air compressors of D20/26 engines

Engine model

Speed factor

Hydraulic pump

Volume per revolution

in cm³

Pressure during constant operation in bar

D20

und

D26

1,194

Hydraulic pump

32

250

22,5

230

11

280

Dual hydraulic pump

22,5 + 32

230

11 + 22,5

230

The single-cylinder air compressor is able to deliver the following torque:

• Lower power take-off: max. 180 Nm

Hydraulic pumps cannot be fitted to the air compressors of six-cylinder engines in the D38 model range.

Please note that the hydraulic pumps on the air compressor are not connected with the compressor output shaft when the vehicle is delivered. The driver plates located in the interior of the vehicle first have to be installed.

This prevents the pumps running dry and possibly being damaged.

Optionally, a dual-circuit hydraulic system (e.g. for operating a snowplough and a gritter) can be delivered ex works.

On vehicles equipped with MAN HydroDrive the supply pump for the hydrostatic drive is attached to the lower output shaft. In this case it is not possible to attach an additional hydraulic pump.

On vehicles equipped with Air Pressure Management (APM) - that is, with an air compressor that switches off automatically - it is currently not possible to attach power take offs to the air compressor.

Any possible changes can be found in the sales systems.

3.1.3 Camshaft power take-off, flywheel-side power take-off

The output point is at the rear end of the engine. These power take-offs are not switchable but are permanently engaged. However, the bodybuilder many install an electromagnetic coupling in the propshaft train.

The camshaft power take-off is available for engines with the D28 designation (vehicles in the model ranges F2000, E2000 and TGA built up to 2003).

The flywheel-side power take-off can be delivered for the 6-cylinder D20/D26 engines (vehicles in the model ranges TGA and TGS/TGX) and D08 engines (vehicles in the model ranges TGL and TGM).

It is not possible to retrofit the flywheel-side power take-off. Preparation for the flywheel-side power take-off is available for the D20/D26 engines. It is then straightforward to retrofit the respective adapter for the propshaft connection or for the direct connection of a pump.

With regard to the variants for the direct fitting of a pump, the following must be observed:

When fitting units (e.g. hydraulic pumps) to the flywheel-side PTO the respective maximum moment of weight must not be exceeded.

In calculating the moment of weight, the weight of

• the pump,

• the fittings,

• the hoses and

• the respective hydraulic fluid

must be considered.

Units with greater moments of weight must be appropriately supported.

It is not permitted to use the gearbox as a support for the pump.

Note:

Prior to assembly of the pump, the shaft/hub connection must be adequately greased with a high-temperature grease as per MAN works standard MAN 284 Li-H2. No pastes containing metal (copper, aluminium, etc.) must
be used.

Important!

The surface of the flange for connecting the pump is treated with preserving wax. Prior to installation of the pump, this surface must be cleaned using commercially available cleaning agents containing solvents, for example
naphtha. The various country-specific regulations concerning disposal must be observed.

MAN works standards can be obtained from http://ptd.mantruckandbus.com - registration is required.

With regard to the variants with output flange, the following must be observed.

It is essential to comply with the maximum permissible propshaft deflection angle of 7° (see also the section entitled “Propshaft connection to power take-off”) and to ensure low-impact and low-vibration operation. In certain cases it may be necessary to modify individual cross members in order to ensure a permissible angle for the propshaft. MAN offers its own solutions for this. If these are inadequate, the planned measures must be approved by MAN beforehand (for address see “Publisher” above).

Flexible double-flange couplings to fit the respective flywheel-side power take-offs are available ex works. It is
mandatory to install them when driving units with an impact factor of Mmax / Mmin ≥ 2. They are also recommended for all other bodies in order to prevent noise / resonance and protect against overloading. Double-flange couplings are to be fitted between the power take-off and the unit to be driven (on the unit side).

A flywheel-side power take-off on vehicles in the TGL/TGM model ranges is possible only in conjunction with
C or crew cabs. The flywheel side PTO is available independently of the cab for vehicles complying with exhaust standard Euro 6.

Variant up to Euro 4:

• Flange Ø 100 6-hole 8 mm

• Speed = 1.195 x engine speed

• Direction of rotation same as engine, anticlockwise as seen in direction of travel.

Fig. 15: Variant for direct connection of pump as per SAE-B for the six-cylinder D08 engine

1) Center of crankshaft

Fig. 16: Overview of hub profiles

Table 04: Hub profiles

Nominal size

Pitch (module) P

Pressure angle

No. of teeth Z

7/8“

16/32

30°

13

1“

13/32

30°

15

3.1.4 Power take-off on transfer

On the two-gear version of the transfer case (in each case with driver-engaged off-road ratio) a flange for a power take-off can be installed in addition to the output points for the front and rear axles. Transfer cases enabling a power take-off are listed in Table 04+05. The output point is at the rear of the transfer case (see Fig. 17+18).

The power take-off can be engaged and disengaged independently of gear changes or the additional off-road transmission ratio in the transfer case. The transfer-case power take-off can also be used when the vehicle is stationary. For this purpose, a gear must be engaged and the transfer case placed in neutral. However, on vehicles equipped with ZF TipMatic gearboxes it is currently not possible to operate the power take-off on the transfer case while the vehicle is stationary.

Operating the transfer-case power take-off in reverse gear while the vehicle is stationary is not permitted. The transfer-case oil pump supplies oil only during operation in the forward gears. If the power take-off is operated while reverse gear is engaged, the oil supply is not ensured. This will result in damage to the transfer case.

Currently, whenever a transfer-case power take-off is selected a cooling package for cooling the transfer-case oil is automatically also installed.

Regardless of the nature of power take-off operation, the following apply:

• The power take-off rotates only when a gear has been selected.

• The direction of power take-off rotation in forward gear is in anticlockwise rotation (looking in the direction of travel)

If the transfer-case power take-off is required while the vehicle is stationary, the transfer case must be set to neutral. The required power take-off drive ratio with the vehicle stationary is obtained by selecting any gear at the main gearbox. The power take-off ratio with the vehicle stationary is thus equivalent to the corresponding main gearbox ratio.

2. Distance-dependent operation

Attached implements required to perform a given number of rotations for a given road distance must be driven by a distance-dependent power take-off. Since the transfer case output is governed by both the on-road and off-road ratio groups, two different ratios can be selected for distance-dependent operation.

Distance-dependent operation of the power take-off depends on:

• the transfer case ratio (the selected on- or off-road gear),

• the final drive ratio at the driven axle(s) and

• the tyre size

As a parameter for the ratio, the number of power take-off revolutions per metre of distance covered can be stated, or alternatively the reciprocal value, that is to say the distance covered in metres per revolution of the power take-off. In the distance-dependent mode, the main gearbox ratio and the engine speed are not the fundamental factors governing the power take-off ratio.

3.2 Gearbox power take-off

3.2.1 Differentiation

Power take-offs can be differentiated on the basis of the following criteria.

• The duration of operation

- Brief operation < 30 minutes

- Brief operation < 60 minutes

- Continuous operation >= 60 minutes

• The power flow on which they are dependent

- Clutch-dependent power take-off

- Engine-dependent power take-off

3.2.2 Clutch-dependent power take-off

In the gearbox, one pair of gears is driven via the main shaft (also the gearbox input shaft) when the engine is running and the clutch is engaged. This causes the countershaft to rotate as well. When the clutch is operated, internal resistance to rotation in the gear train causes the countershaft to come to a standstill. In this operating condition the power take-off can be engaged.

The drive ratio between engine and gearbox is determined by the ratio of the gear pair between the main shaft and the countershaft.

If identical power take-offs are fitted to different gearboxes, their speed factors (f) will vary according to the basic gearbox ratio.

If appropriate electrical preparation has been installed, clutch-dependent power take-offs can be retroﬁtted to the end of the gearbox. Without the electrical preparation, the effort involved in retrofitting wiring is considerably greater. For more precise information on effort and costs, please contact your MAN Service outlet. If you have any questions regarding power take-off design, please contact MAN (for address see “Publisher” above).

The power take-off is engaged pneumatically via a switching valve and a pneumatic cylinder, located inside the PTO housing, which is pressurised on one side.

Fig. 14: Engaging the ZF power take-off

1) Sensor „I/O“

2) Air pressure connection

3) Main output flange

4) Air reservoir

5) Shift valve

6) OFF – Reset by spring force

7) ON - actuation through compressed air

Operation:

It is possible to operate the power take-off both when the vehicle is stationary and when it is in motion.

However, the power take-off may be turned on and off only when the vehicle is stationary.

If clutch-dependent power take-offs are operated whilst the vehicle is in motion then there may be no gear changes.

On vehicles fitted with a TipMatic gearbox, the gears listed in the table below are available when the power take-off is turned on. Gear change is only possible when the vehicle is stationary. Changing gear while driving is not possible.

Table 07: Gears available on TipMatic gearbox with power take-off active

Gearbox type

Direction of travel

Forwards

Reverse

For DD gearboxes (direct drive)

1, 3, 5

1

For OD gearboxes (overdrive)

2, 4

2

The following safety notes must be observed.

• The power take-off may only be turned on or off with the clutch disengaged manual gearbox) or with the DNR switch in the neutral position (TipMatic gearbox)!

• The engine must be at idling speed when disengaging.

• Only turn the power take-off on when the countershaft is stationary. Grating will occur if the power take-off is turned on with the countershaft still rotating.

Coast-down times are different depending upon the operating conditions and may be shortened by brief asynchronisation, preferably with first gear, when a manual gearbox is fitted. When a TipMatic gearbox is fitted, due to the nature of the system it may take a few seconds for the power take-off to become active subsequent to the request.

Caution: When the vehicle is at rest the pressure in the system slowly drops. This causes the claw-type coupling located above the pressure spring in the shift cylinder to disengage. As soon as the air pressure in the system increases once more (as a result of the engine being started), it will engage again automatically. With the engine running, this causes damage to the switching-gear teeth and leads to premature failure of the power take-off.

For this reason, if the vehicle is to be switched off for any length of time (e.g. overnight) the power take-off must be turned off.

Power take-off designations:

The last letter in the power take-off designation, that is to say the letter “b” or “c”, indicates the type of output.

One must distinguish between two versions.

• Version “b”

This is the basic version for driving propshafts and is fitted with a flange as per DIN ISO 7646.

• Version “c”

This is the simplest and most commonly-used type for the direct connection of pumps.

Depending on the design of the power take-off, Version “c” can be converted to Version “b” and vice versa.

Information on feasibility and the effort involved can be requested from MAN (for address see “Publisher” above).

Fig. 21: Connection variants for power take-offs

When connecting pumps directly to Version “c”, the bodybuilder must ensure that the maximum permissible moment of weight of a directly-connected pump with its fittings (e.g. hydraulic hoses, hydraulic oil, etc.) is not exceeded.

The engine-dependent power take-offs are those models with the designation “NMV”. These power take-offs are connected directly to the engine’s crankshaft, see Fig. 24. They are rated for continuous operation and high output. Engagement is achieved using an internal, hydraulically actuated multi-disc clutch and the output point
of the NMV can therefore be engaged and disengaged under load.

Heavy impact loads can result in damage to the NMV’s multiple-disc clutch and the vehicle’s clutch, extending as far as the destruction of the power take-off! Although operation of the NMV is in principle independent of the vehicle’s clutch, impacts are transmitted through the driveline and have an effect on the clutch when it is engaged. Damage can thus also be caused here.

If the body is operated while stationary (gearbox in neutral) for more than 10% of its overall operating time, damage to the pre-damper unit of the vehicle's clutch may result. Only vehicles whose bodies are driven by the NMV are affected, for example suction excavators, concrete pumps, wood cutters. In the event of such damage occurring, it is possible to install a clutch drive plate without pre-damper unit. This clutch drive plate without pre-damper unit is available on new vehicles as special equipment. You can obtain information from MAN (for address see “Publisher” above).

The given output torques are guideline values for degree of uniformity 1, i.e. for operation free of impact and vibration. In the case of critical applications, for example wood cutters, consultation with MAN is necessary (for address see “Publisher” above). If there is a risk of overloading power take-off due to excessive power being taken off, it is possible to limit engine torque by means of a parameter.

Due to the existing drag torque of the multiple-disc clutch, the NMV’s output flange also rotates when not engaged. At an engine speed of 1300 rpm and an operating temperature of 40°, this residual torque is approximately 10 Nm. It can only be ensured that the output flange is stationary when the counter-torque of the unit to be driven is > 10 Nm. This must be taken into consideration especially with regard to driving easy-running units, for example the centrifugal pumps employed by fire brigades.

Currently, selection of the NMV automatically includes installation of a heat exchanger that uses engine coolant to cool the gearbox oil.

For heavy operation and continually high power take off, an external cooling system with a separate heat exchanger for cooling the gearbox oil is available.

• The engine-dependent power take-off can be operated when the vehicle is moving and when it is stationary.

• The engine-dependent power take-off is ready for operation as soon as the engine is running but can be engaged only at engine speeds greater than 800 rpm.

• The transmission of force to the power take-off is fully independent of the vehicle‘s clutch.

There are two basic types: NMV130E with the ZF-Ecomid gearbox 16S109 (M2000L/M model range) and NMV221 with the ZF-Ecosplit gearboxes ≥ 16S….

Both of these can alternatively be supplied with two different ratios:

NMV130E:

Speed factor f = 1.03 • nmot, with a maximum torque of 1400 Nm

Speed factor f = 1.47 • nmot, with a maximum torque of 1400 Nm

NMV221

Speed factor f = 0.98 • nmot, with a maximum torque of 2000 Nm

Speed factor f = 1.55 • nmot, with a maximum torque of 1300 Nm

Important operating instruction with regard to the minimum speed during operation:

A power take-off under load requires a minimum engine speed of 800 rpm. If oil pressure is too low the clutch may slip and be damaged as a result of the ensuing heat.

An operating speed of 800 to 1200 rpm requires a mass moment of inertia at the power take-off of > 0.4 Kgm2. If the mass moment of inertia of its equipment is unknown to the bodybuilder, then an operating speed of > 1200 rpm should be selected at the power take-off in order to remain above the resonant speed. Ideally, operation should be within the decoupling limit range or above it (see Fig. 25).

The use of a converter-clutch unit enables smooth pulling away and precise manoeuvring even with heavy train weights under conditions of almost no wear. The hydrodynamic torque converter makes it easy to pull away with heavy loads. After pulling away, the torque converter lock-up clutch forms a direct, mechanical connection between input and output sides, thus increasing driveline efficiency.

Use of a converter-clutch unit does not change the installation situation for power take-offs at the end of the gearbox. However, the broader size of the converter-clutch unit means that the installation location is moved backwards, towards the frame end.

Clutch-dependent power take-offs attached to gearboxes with converter-clutch units differ in their function, operation and effect from those attached to gearboxes without.

Up to a speed of approx. 1000 rpm, the converter is “open”, i.e. there is no mechanical connection between the input and output sides. If a clutch-dependent power take-off is mounted on a gearbox with converter-clutch unit, it is essential to take into account that because of the operation in conversion range, a constant drive ratio is not always maintained. Resulting from the operating principle of the hydrodynamic torque converter, at a constant engine speed the output speed at the power take-off may vary quite extensively due to slip in the converter.

Theoretically the speed at the power take-off could drop as far as zero if the load on the power take-off is large enough to cause so much slip in the converter that power can no longer be transmitted.

For stationary operation of the power take-off, this effect can be avoided by installing a so-called bridging circuit.

This engages the lock-up clutch automatically when the power take-off is engaged.

As a result, a mechanical link is formed between the engine and the power take-off and the gear ratio is constant.

The bridging circuit is offered only in conjunction with a gear-shift inhibitor, which prevents a gear being selected accidentally when the power take-off is engaged.

In non-stationary operation of the power take-off, converter slip and the resulting fluctuation of speed and output torque must be taken in consideration.

3.2.5 Power take-offs on ZF HP automatic gearboxes

The ZF HP 500, ZF HP 590 and ZF HP 600 automatic gearboxes with torque converter can be supplied with up to two engine-speed-dependent power take-offs

Power take-off variants D01, D02 and D05 can be fitted either left or right of the main output flange. Variant D05 with spur pinion can also be rotated and fitted at a positioning angle alpha of 60°, 120° and 300°.

The direction of rotation depends on the installation location (on the left or right of the gearbox main shaft).

Please note that power take-offs D01 and D02 installed to the left of the main output flange (eleven o’clock) rotate clockwise, while power take-offs D01 and D02 installed to the right of the main output flange (one o’clock) rotate anticlockwise.

Fig. 27: Power take-offs D01 and D02: installation locations and directions of rotation

A “11 H“ position

B “1 H“ position

Power take-off D05 is equipped with a spur pinion. This means that the power take-off fitted to the left of the main output flange rotates anticlockwise and the power take-off fitted to the right of the main output flange rotates clockwise.

Fig. 28: Power take-off D05 with spur pinion

For this reason the installed position is stated together with the power take-off designation, for example, “D02c links” (left) is for installation to the left of the main shaft.

Important! “Links” (left) and “rechts” (right) here refer to the installation location on the gearbox and not to the direction of rotation.

The power take-offs on the HP gearbox can be engaged under load and can be used independently of the shift position of the gearbox. The power take-offs can be engaged and operated both when the vehicle is stationary and when it is in motion.

The permissible engine speeds must be observed when the power take-offs are engaged.

It is possible to retrofit the power take-offs on all HP gearboxes installed by MAN.

3.2.6 Power take-offs and Intarders

The ZF Intarder is the gearbox housing is an integrated secondary retarder (a hydrodynamic auxiliary brake).

The Intarder is available for 12AS... and 16S... gearboxes and does not impair the operation of any power take-offs fitted to the end of the gearbox.

Fig. 30: TipMatic gearbox with Intarder (IT3)

1) Control unit for Intarder 3

2) Intarder 3

3) Gearbox TipMatic

4) Heat exchanger (stainless steel)

Some power take-offs that can be fitted in conjunction with the Intarder require an adapter kit or are special power take-offs.

Fig. 31: Power take-off variant N221/10 with and without

N221/10 (without Intarder) N221/10 (with Intarder)

3.2.7 Power take-offs with MAN HydroDrive

The combinations of MAN HydroDrive and power take-offs currently possible can be found in the current sales systems.

The combination of MAN HydroDrive and a power take-off fitted to the air compressor is not possible because the output point on the air compressor is occupied by the supply pump for the HydroDrive system.

3.2.8 Power take-offs on ZF gearboxes (technical specifications and tables)